I feel. Honestly I don't understand people that have high scores consistently (aka Feralis...his practice tests are soooo consistent). Anyway I don't think you should worry about it. We have good and bad days. I think it's important to mentally prepare yourself for the DAT...to know that you will do your very best and that you will be focused on the test day.
Have you taken a full 4:15 test in one sitting? I started doing that this week and it was sooo hard for the first two days. I couldn't have done it on the test day.
Also, when you take a full test take some time and imagine this is the real test and force yourself to fully focus...if you do this a few times and try your best I think you will be prepared on the test day and you will be constant.
Also, don't tire out yourself this week. I'd rather go over the details you're struggling with and do it in small bits. Gets lots of sleep and again I think it's very important to mentally prepare yourself. My DAT is coming up in less than 3 weeks so I'm starting to feel the pressure.
But hey it's gonna pass! And if you studied and did your best you'll do great 😉